13. Prolonged exposure to movement in one direction _______ the motion detectors sensitive to that direction. When the movement stops, the baseline firing rate of detectors for the opposite direction of motion will be _______ than the firing rate for the detectors that responded to the prolonged movement, leading to motion aftereffects. (A) activates; higher (B) activates; lower (C) fatigues; higher (D) fatigues; lower